Generally, a light emitting diode (LED) includes an LED chip and an encapsulating layer covering the LED chip. The LED generally generates a smooth round light field with a radiation angle of 120 degrees (i.e. ±60 degrees). However, the light emitted from the LED still has a bigger angle relatively to the optical axis. the light intensity concentrated at a center of the LED is not strong enough. The LED cannot be used in special place which needs a smaller angle and strong concentrated light, such as engraving machine, cutting tools and product display ark etc.